A typical cellular wireless network includes a number of base stations each radiating to define a respective coverage area in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices (whether or not user operated), can operate. In particular, each coverage area could operate on one or more carriers each defining a respective frequency bandwidth of coverage. In turn, each base station could be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a UE within coverage of the network could engage in air interface communication with a base station and could thereby communicate via the base station with various remote network entities or with other UEs served by the base station.
Generally, a base station in a wireless communication system can take various forms. For instance, the base station could be a macro base station that provides a broad range of coverage and could thus include a tall antenna tower and a power amplifier for providing high transmission power. Alternatively, the base station could be a small-cell base station (“small cell”), such as a femtocell and/or a relay base station, typically having a much smaller form factor and operating at lower transmission power for providing a smaller range of coverage.
Further, a cellular wireless network could operate in accordance with a particular air interface protocol (radio access technology), with communications from the base stations to UEs defining a downlink or forward link and communications from the UEs to the base stations defining an uplink or reverse link. Examples of existing air interface protocols include, without limitation, Long Term Evolution (LTE) (using Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA)), Code Division Multiple Access (CDMA) (e.g., 1×RTT and 1×EV-DO), Global System for Mobile Communications (GSM), IEEE 802.11 (WIFI), BLUETOOTH, among others. Each protocol could define its own procedures for registration of UEs, initiation of communications, handover between coverage areas, and other functions related to air interface communication.
In accordance with various industry standards, a base station could provide multiple cells in various directions and/or on various carrier frequencies, and each such cell could have a respective coverage identifier. For example, in accordance with a recent version of the LTE standard, each base station could have a global base station ID and each cell of a base station could have a cell ID. Thus, at the system level, each combination of global base station ID and cell ID could define a network identifier for a cell (which could also be referred to as a globally unique identifier). In LTE, this network identifier is known as an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) cell global identifier (ECGI). Moreover, in terms of air interface coverage, each cell provided by the base station also has a physical cell identifier (PCI) that is identifiable by a UE. While a network identifier is globally unique within a public land network, there are only 504 possible PCIs. Thus, PCIs are likely to be repeated many times throughout a public land mobile network.
In a system arranged as described above, PCI(s) and network identifier(s) could help facilitate handover processes. For example, when a source base station is serving a UE and the UE detects sufficiently strong coverage from a target cell of a target base station, the UE could send a measurement report to the source base station indicating signal strength (e.g., a received strength or signal-to noise ratio) for the target cell and specifying the target cell's PCI. The source base station could in turn determine if applicable handover thresholds are met. And if so, the source base station could then use a network identifier of the target cell as basis to engage in handover signaling with the target base station to orchestrate handover of the UE to the reported target cell.
More specifically, given that the target cell's network identifier is defined by the combination of the target base station's global base station ID and the target cell's cell ID, the source base station could use the global base station ID and the cell ID to facilitate handover of the UE to the reported target cell. For instance, the source base station could use the global base station ID of the target base station as basis for transmitting to the target base station, either over a direct inter-base-station interface or through one or more other network entities, a handover request message that requests the target base station to provide service to the UE through the target cell. And the handover request message could specify the target cell using the cell ID of the target cell. In this way, the target base station could then engage in a handover preparation process to establish a radio link for the UE in the target cell, and the UE could then ultimately transition to be served by the target cell.
Generally, the source base station could have access to the network identifier of the target cell through a neighbor list that the source base station (and/or other network entity) maintains. In particular, the neighbor list may list neighboring cells and, for each listed neighboring cell, may include a mapping of that cell's PCI to a network identifier of that cell. As such, if the source base station decides to trigger handover of the UE to a target cell of a target base station, the source base station could then refer to the neighbor list in order to determine the network identifier of the target cell based on the reported PCI of the target cell. And the source base station could then use the determined network identifier to facilitate handover of the UE to the target cell as discussed above.